Two new advanced ultrasound imaging technques are proposed for potential application in breast cancer screening and diagnosis. These techniques will be evaluated using test objects and tissue specimens. In particular breast specimens from mastectomy will be scanned which will be intact except for a needle biopsy or excisional biopsy. Following scanning the specimen will be sectioned, fixed, stained, cleared and photographed for comparison with the ultrasound scan images. A pathologist and ultrasound radiologist will assist in these comparisons. The results of these tests will be used to complete an engineering feasibility study for future clinical scanners. A reflection imaging technique, synthetic focusing, is similar to seismic methods used in geophysical surveys. Laboratory test indicate a resolution of less than one mm is possible. A second imaging technique, diffraction tomography with spherical insonification, is formulated to produce images of refractive index and attenuation also at a resolution of about one mm or less.